On 16.07.2026 10:27, Steven Price wrote:
> On 13/07/2026 09:48, Adrián Larumbe wrote:
> > When a VM is created, caller has to specify the range of the address space
> > carve-out set aside for mapping kernel BO's. That means vm_bind mappings of
> > UM-exposed BO's should not intersect with that region, but at the moment
> > we're not checking this.
> >
> > At first, I thought of giving these values to drm_gpuvm_init() through its
> > reserve_{offset, range} arguments, but it turns out that is meant for VM
> > address spans that are not managed through the usual drm_gpuvm split/merge
> > circuit, so storing the end of the user VA range at VM creation time and
> > doing a quick check in the vm_bind ioctl path was the simplest workaround.
> >
> > The new check also makes sure vm_bind range doesn't overflow the size of a
> > 64-bit unsigned integer. That was already being done further down the call
> > stack inside drm_gpuvm_sm_map -> drm_gpuvm_range_valid, but it's best to
> > fail early in the driver before GPUVM functions are invoked so that we
> > won't waste time allocating vm_bind context resources.
> >
> > Fixes: tag and reference the relevant sparse binding support commit.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Can you dig out the relevant commit ;)
Oops. Will do.
> > Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
> > Reviewed-by: Boris Brezillon <[email protected]>
> > Signed-off-by: Adrián Larumbe <[email protected]>
>
> Reviewed-by: Steven Price <[email protected]>
>
> Thanks,
> Steve
>
> > ---
> > drivers/gpu/drm/panthor/panthor_mmu.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c
> > b/drivers/gpu/drm/panthor/panthor_mmu.c
> > index 31cc57029c12..910c8e579770 100644
> > --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> > @@ -310,6 +310,9 @@ struct panthor_vm {
> > u64 end;
> > } kernel_auto_va;
> >
> > + /** @user_va_range: Upper boundary of VAs VM users can map objects
> > against. */
> > + u64 user_va_range;
> > +
> > /** @as: Address space related fields. */
> > struct {
> > /**
> > @@ -2893,6 +2896,8 @@ panthor_vm_create(struct panthor_device *ptdev, bool
> > for_mcu,
> > va_range = full_va_range;
> > }
> >
> > + vm->user_va_range = kernel_va_start;
> > +
> > mutex_init(&vm->mm_lock);
> > drm_mm_init(&vm->mm, kernel_va_start, kernel_va_size);
> > vm->kernel_auto_va.start = auto_kernel_va_start;
> > @@ -2981,6 +2986,10 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
> > if (!IS_ALIGNED(op->va | op->size | op->bo_offset, vm_pgsz))
> > return -EINVAL;
> >
> > + /* We don't allow mappings that overlap with kbo's reserved range */
> > + if (range_overflows(op->va, op->size, vm->user_va_range))
> > + return -EINVAL;
> > +
> > switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
> > case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP:
> > if (!(op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE)) {
> >
Adrian Larumbe
